A sign warns people not to enter the town of Ozersk, Chelyabinsk region, Russia, which houses the Mayak nuclear facility. In 1957, the nuclear reprocessing plant was the site of one of the world's worst nuclear accidents.

Katherine Jacobsen
/ AP

Originally published on December 8, 2017 10:15 pm

More than two months after a mysterious radioactive cloud was detected over Europe, Russia's nuclear industry went public Friday in an attempt to dispel fears that one of its facilities had released a plume of ruthenium-106.

Russia's state nuclear corporation, ROSATOM, released the findings of a special commission, which concluded that the Mayak nuclear reprocessing plant, near the border with Kazakhstan, could not have been the source of ruthenium-106, a radioactive isotope.

European monitoring stations first picked up traces of ruthenium in the air in late September. While concentrations were too low to pose a health risk in Europe, scientists have been puzzling over its origin. Wind patterns pointed to the south Urals, where the Mayak facility is located. The plant was the site of a 1957 explosion widely considered to be one of the world's worst nuclear disasters.

In November, Russia's meteorological service said that on Sept. 26, ruthenium-106 levels in a town 20 miles from the Mayak plant, Argayash, had exceeded the previous month's by 986 times.

The same day, Mayak flatly denied that the spike in ruthenium had anything to do with its activities.

The ROSATOM commission that inspected the Mayak facility afterward reached the same conclusion. The commission said it hadn't detected abnormal levels of ruthenium at the facility, there had been no malfunction of monitoring systems and none of the 250 Mayak employees tested had shown any trace of the isotope.

Arutyunyan rejected the suggestion that officials have been slow in informing the public, saying there had been no emergency situation that would have warranted an alarm. He called talk of a danger to health "nonsense."

"Why should we come running to announce something? Mayak told us that all their systems were working absolutely normally and routinely," he said. "Why should they have jumped up and shouted? I think we spent the right amount of time to understand what happened."

Environmental activists and government critics disagree.

After the findings of the commission were released, Greenpeace Russia started a petition drive addressed to the general prosecutor's office, demanding an investigation by independent specialists and public figures into a possible release of ruthenium from Russian territory, as well as into the possible concealment of information by ROSATOM.

"The question is not only about the immediate danger, but the origin of this release," Greenpeace energy campaigner Rashid Alimov said in a phone interview. "We think such incidents should be investigated and there must be an answer."

Finding the source of the radioactive cloud was beyond the scope of the ROSATOM commission. But because the ruthenium-106 over Europe was found alone, that is, unaccompanied by other radioactive isotopes, the commission said nuclear power plants or spent nuclear fuel processing facilities like Mayak could be excluded as sources because they don't produce "pure" ruthenium-106.

The commission said a satellite — or a fragment of one — re-entering the atmosphere cannot be completely ruled out as the source of the ruthenium.

"What's happening with the ruthenium cloud reminds me a lot of what went on with Chernobyl," Russian opposition leader Alexei Navalny said in a recent video blog. "In no way do I want to prove there's been a catastrophe of that scale. I just want to say that the pattern of behavior is exactly the same."